System and method of communicating in a welding system over welding power cables

ABSTRACT

Systems and methods of the present invention are directed to welding systems having a welding power supply and wire feeder, where the power supply and wire feeder communicate over the welding power cables. In exemplary embodiments, the wire feeder communicates with the power supply over the welding cables using current draw pulses which are generated and recognized by the power supply. Similarly, the power supply generates voltage pulses which are transmitted over the welding power cables and recognized by the wire feeder.

PRIORITY

The present application is a continuation of U.S. patent applicationSer. No. 15/294,653, filed on Oct. 14, 2016, the entire disclosure ofwhich is incorporated herein by reference, and which claims priority toU.S. Provisional Patent Application Ser. No. 62/248,034 filed on Oct.29, 2015, the entire disclosure of which is incorporated herein byreference.

FIELD OF THE INVENTION

Devices, systems, and methods consistent with the invention relate todata communication in welding systems, and more specifically related todata communication over welding cables.

BACKGROUND OF INVENTION

As welding technology and applications have advanced so have the demandson power supply sources and welding systems. These demands haveincreased with the increased use of welding systems in more ruggedenvironments. In traditional welding systems the welding power supplycommunicates with the wire feeder via dedicated communication cables.However, these communication cables are susceptible to damage,especially in these rugged environments. Further, the communications addcost and complexity to the welding system and can limited thepositioning of the wire feeder relative to the power supply. Effortshave been made to allow for system communication over the power cables,but these efforts use complex communication protocols which can becomplex and vulnerable to interference and other issues.

Further limitations and disadvantages of conventional, traditional, andproposed approaches will become apparent to one of skill in the art,through comparison of such approaches with embodiments of the presentinvention as set forth in the remainder of the present application withreference to the drawings.

BRIEF SUMMARY OF THE INVENTION

Embodiments of the present invention include employing welding cablesthat facilitate bi-directional data communications between a wire feederand a power supply. The circuitry included inside the wire feeder andthe power supply allow for such communications to take place before,after and/or concurrently with transfer of welding power signals.Communication modules included within the wire feeder and the powersupply allow for communication using current and voltage pulses over thewelding signal cables and do not require the use of complexcommunication protocols.

In further exemplary embodiments, a method is provided which comprisesreceiving continuously worksite voltage measurement data of voltage at awelding electrode, the worksite voltage measurement data is communicatedacross the arc using a welding cable and comparing continuously theworksite voltage measurement data to a welding output voltage at thewelding power supply to identify a voltage difference. The method alsoincludes increasing or decreasing the welding output voltage using thewelding power supply based at least in part on the voltage difference.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and/or other aspects of the invention will be more apparent bydescribing in detail exemplary embodiments of the invention withreference to the accompanying drawings, in which:

FIG. 1 illustrates a diagrammatical representation of an overall weldingsystem in accordance with an exemplary embodiment of the presentinvention;

FIG. 2 illustrates a diagrammatical representation of an exemplarycurrent signal communication waveform to be used by an exemplaryembodiment of the present invention;

FIG. 3 illustrates a diagrammatical representation of an exemplaryvoltage signal communication waveform to be used by an exemplaryembodiment of the present invention;

FIG. 4 illustrates a diagrammatical representation of an exemplaryembodiment of a communication module in an exemplary wire feeder of thepresent invention; and

FIG. 5 illustrates a diagrammatical representation of a furtherexemplary embodiment of a communication module in an exemplary wirefeeder of the present invention.

FIG. 6 illustrates a diagrammatical representation of another of anexemplary circuit representation of a welding output circuit path of atleast FIG. 7, in accordance with an embodiment of the presentinnovation;

FIG. 7 illustrates a diagrammatical representation of a schematic blockdiagram of another exemplary embodiment of a welding system including awelding output circuit path;

FIG. 8 illustrates a diagrammatical representation of another schematicblock diagram of a further exemplary embodiment of a welding systemincluding a welding output circuit path;

FIG. 9 illustrates a diagrammatical representation of a schematic blockdiagram of an additional exemplary embodiment of a welding systemincluding a welding output circuit path; and

FIG. 10 illustrates a diagrammatical representation of a flowchart of anexemplary embodiment of a method for controlling a welding outputelectrical characteristic.

DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS

Reference will now be made in detail to various and alternativeexemplary embodiments and to the accompanying drawings, with likenumerals representing substantially identical structural elements. Eachexample is provided by way of explanation, and not as a limitation. Infact, it will be apparent to those skilled in the art that modificationsand variations can be made without departing from the scope or spirit ofthe disclosure and claims. For instance, features illustrated ordescribed as part of one embodiment may be used on another embodiment toyield a still further embodiment. Thus, it is intended that the presentdisclosure includes modifications and variations as come within thescope of the appended claims and their equivalents.

Turning now to the figures of the present application, FIG. 1 depicts anexemplary welding system 100 in accordance with an embodiment of thepresent invention. The welding system 100 can be any known type ofwelding system which employs a welding power supply and a wire feedercoupled to the power supply. For example, the welding system can be aMIG type welding system. The embodiments discussed below will generallybe described as a MIG welding system, but this is intended to be onlyexemplary, as embodiments of the preset invention can be employed inother types of welding systems. Because MIG type welding systems arewell known, the coupling of the system (e.g., wire feeder) to thewelding torch and workpiece is not shown for clarity. That aspect of theembodiments of the present invention are not changed and thus need notbe shown or discussed in detail herein. In further exemplaryembodiments, the system can include a remote control and/or a pendantcontrol device (which are generally known) which utilizes thecommunication methodologies discussion herein. That is, for example, theremote/pendant can utilize the across the arc communication protocolsdiscussed herein and otherwise detect the signals being sent by any oneof the wire feeder or power supply and communicate those signals to auser. In other embodiments the pendant/remote controller takes the placeof the wire feeder in the systems described herein and the functionalitydescribed below in the wire feeder would be present in thependant/remote control, using similar communication protocols asdescribed herein. For example, in a stick or TIG welding system theremote would be used instead of the wire feeder and the remote will becoupled to the power supply and communicate as described herein. Itfurther should be noted that while the exemplary embodiments describedherein are described as welding systems, embodiments of the presentinvention can also be used in other systems, such as plasma cutting,etc., and as an extension, other components can be used, instead of awire feeder and welding power supply as described herein. That is, thepower supply can be a cutting power supply, power generator with a load,etc. The systems are described herein as welding for simplification andefficiency, but embodiments herein are not limited thereto. Further, thecommunication circuitry, systems, methods and protocols described hereincan be incorporated into these types of other systems by those of skillin the art.

Turning now to the system 100, as is typical, the system 100 contains apower supply 110 coupled to a wire feeder 120 via welding cables 130.The power supply 110 can be configured like known welding powersupplies, with the additional features and attributes discussed herein.For example, in embodiments of the present invention, the power supply110 can be configured like the Flextec® welding systems manufactured byThe Lincoln Electric Co. of Cleveland, Ohio. Further, the wire feeder120 can be configured like known wire feeders, with the additionsdiscussed herein, an example of which is the LN-25 series wire feedersmanufactured by The Lincoln Electric Company of Cleveland, Ohio. Ofcourse other power supplies and wire feeders can be used and thesereferences are intended to be merely exemplary.

As is general known, the power supply 110 outputs a welding current,which is directed to the wire feeder 120, via the cables 130, so thatthe wire feeder can pass the current on to a welding electrode forwelding a workpiece. In a MIG system the electrode is also theconsumable, and in other processes, such as TIG, the electrode is notthe consumable deposited into the weld. The cables 130 are the mainwelding power cables which deliver the welding power/current from theoutput studs 111/112 of the power supply 110 to the wire feeder 120. Aswith known systems, the wire feeder 120 and the power supply 110 cancommunicate with each other both prior to, after and during welding.Often these communications are related to welding parameters, setpoints, feedback, etc. As explained previously in known systems, thewelding systems use dedicated communication cables/lines between thepower supply 110 and the wire feeder 120. Embodiments of the presentinvention eliminate the need for these additional communication cablesand provide a robust communication system/process between the wirefeeder and power supply.

As described further below, in addition to being able to carry thewelding current/power the welding cables 130 are designed to carry datacommunications (e.g., control commands) between the power supply 110 andthe wire feeder 120. Embodiments of the present invention supportuni-directional as well as bi-directional communication between the wirefeeder 120 and the power supply 110. Accordingly, the power supply andthe wire feeder both transmit/receive signals and/or data with respectto each other over the cables 130.

As is generally understood, the power supply 110 receives an AC signalas its input (not shown in FIG. 1). The AC signal can be received as a3-phase input, or a single phase AC input signal. The AC signal can varyin voltage and frequency depending on the source of power and/or thecountry of operation. For example, the AC input can be from a utilitygrid—which can range from 100 to 660 volts at 50 or 60 Hz—or can be froma portable generator, which can also have a varying voltage andfrequency. Thus, the system 100 is capable of operating properly andproviding a welding or cutting signal regardless of the input AC voltagemagnitude, phase type and frequency. The power supply 110 is designed torun in various modes including constant voltage (CV) and constantcurrent (CC) modes, as suitable in various applications. Thus, the powersupply 110 can include additional electrical components to condition theraw AC signal received and output the desired welding signal.

In most exemplary embodiments, the power from the power supply 110 issuitable for welding and is transmitted to the wire feeder 120 via thewelding cables 130—which are large diameter electrical conduits. Thus,in exemplary embodiments of the present invention, the welding signal(i.e., the current signal sent to the contact tip that is actually usedfor welding) is originally generated, controlled and modified within thepower supply 110, and then communicated via welding cables 130 to thewire feeder 120. In addition to feeding a welding electrode, the wirefeeder 120 passes on the received welding signal to the arc using cables(not shown).

In traditional welding systems, sense leads are often used to sense avoltage of the welding arc to allow for proper control of the weldingoperation. The sense leads are electrically coupled to the workpiece andthe contact tip to provide feedback regarding the voltage of the arc.This feedback is used by the power supply 110 to control the creationand output of the welding signal. For example, the sense leads would beused to detect a short circuit event and the power supply 110 wouldoutput a signal which allows for the short to be cleared. The senseleads are not shown in the figures for clarity, but their use is wellknown and need not be further described herein.

For example, it is noted that in some applications, the wire feeder 120is positioned a significant distance from the power supply 110, thusrequiring the cables 130, and any other data carrying or sense leadcables, to be quite long. This often occurs when the welding operationis not conducive to having the power supply 110 close to the weldingoperation, but the wire feeder 120 is positioned close by to ensureproper wire feeding. These long cables (especially the welding powercables 130) can greatly increase the overall system inductance during awelding operation. This increase in impedance can be a detriment to thewelding operation because it can adversely affect the overallresponsiveness of the welding power supply 110. This is particularlyproblematic in pulse welding operations. Therefore, it is desirable toreduce the overall system impedance as much as possible. Further,separate control cables are typically used to connect the power supplyand the wire feeder. These are prone to damage and other limitations,because of their length.

With embodiments of the present invention, the power supply 110 and thewire feeder 120 can be placed apart from each other by very largedistances, whereas with traditional welding systems there exists amaximum effective distance between the welding power supply and the wirefeeder. For example, traditional systems should not have more than 100feet in between the power supply and the wire feeder. However, withembodiments of the present invention, that distance can be greatlyexceeded. In fact, the components 110 and 120 can be separated from eachother by a distance in the range of 100 to 500 feet. In other exemplaryembodiments the distance is in the range of 250 to 500 feet.

As briefly mentioned above, efforts have been made to address some ofthe issues by communicating over the power cables 130 by super-imposinga communication signal over a welding signal. However, this can havesome severe drawbacks as the communication signal can interfere with, orotherwise comprise the welding signal, and can require complexcommunication control. However, as explained in detail below, theseissues are not present with embodiments of the present communicationsystem. That is, rather than overlaying a communication signal,embodiments of the present invention utilize a regulated/controlledpower draw protocol to communicate between the wire feeder and the powersupply. This is further explained below.

As shown in FIG. 1, the power supply 110 contains a welding power outputmodule 103 which generates and outputs the welding power signal to thewire feeder. The welding output module can be constructed consistentwith known systems, and can contain (for example), a rectifier, a buck,boost or buck-boost circuit to generate a regulated DC bus and an outputcircuit, such as a chopper, PWM, inverter, etc. which is used togenerate the welding signal. Of course, other known outputcircuits/configurations can also be used without departing from thespirit or scope of the present invention. This output module can becontrolled consistent with known systems. The power supply 110 alsocontains a control module 101 which can be used to control the operationof the output module 103 and the power supply 110. The control modulecan contain a processor based computing system containing a memory,processor, etc. to control the operation of the power supply 110consistent with known systems. Further, the control module 101 containsa receiver 105 and a transmitter 107 to facilitate communication withthe wire feeder 120 consistent with the embodiments discussed herein. Asshown, the receiver 105 is coupled to at least one output line of theoutput module 103 with a current sense lead 104 to sense an outputcurrent of the output module 103. Further, the control module 101contains a transmitter 107 which is used facilitate the transmission ofa data signal from the power supply to the wire feeder 120. Thetransmitter 107 is coupled to the output power module 103 via a voltagesignal lead 106—the use of which will be explained further below. Ofcourse, the power source 110 also contains additional components andelectronics, such as input controls, auxiliary power, etc. which are notshown for clarity. However, as these aspects of power supplies are wellknown they need not be discussed in detail herein.

Further, as shown, the wire feeder 120 contains a controller module 121which is used to facilitate communication with the power supply 110. Thecontroller module 121 contains/is coupled to a user interface controlboard 126 which allows a user to input user/welding data to the wirefeeder 120 to control operation of the system 100. The user interface126 can be configured like any known user interface, and can include adata screen (LED, etc.) user controls (knobs, buttons, etc.) and/or atouch sensitive input screen. Any known user interface configuration canbe utilized. In some embodiments, the user interface controls 126 neednot be a part of the communication module, but the user input is atleast coupled to the communication module to allow for the user inputdata to be communicated as discussed herein. The controller module 121also includes a receiver 129 which is coupled to one of the wire feederstuds 113/114 which are coupled to one of the welding power lines 130via a voltage sense lead 128. (While only one sense lead is shown, senseleads to each of the studs can be used to detect voltage at the studs).As explained further below, the voltage sense lead 128 is used to sensea voltage communication signal from the power supply 110. The controllermodule 121 also contains a communication module 123 having a transmitter125 and a current sink circuit 127 which is used to vary the currentdraw in the wire feeder 120 to facilitate communication with the powersupply 110. This is explained further below. Of course, the wire feeder120 can have other systems and components, such as motors, motorcontrols, etc. which are known and need not be shown or described forclarity. The controller module 121 can also have a processor, memory,etc. consistent with known controller modules to ensure the properoperation of the wire feeder 120.

As state above, some systems have been developed which utilize a complexcommunication signal over the power cables 130. Embodiments of thepresent invention do not use this ideology, but instead vary thecurrent/power draw to facilitate communication. Embodiments of thepresent invention are discussed below, in the context of an exemplarycommunication sequence. However, it should be noted that in thefollowing exemplary sequence/embodiment the communication sequencebegins at the wire feeder 120, but embodiments are not limited in thisway as the power supply 110 can initiate communications consistent withembodiments described herein.

As is generally known, the wire feeder 120 can receive its control andoperational power from the power supply 110 via the cables 110. Thisoperational power can be in the form of output voltage from the powersupply 110 having an OCV voltage of about 60 volts (for example), and apower of about 50 watts (for example). (It is noted that while the powersignal is referred to as an OCV signal, there is some current flowingdue to the fact that the power signal from the power supply 110 is beingused to power the auxiliary circuits in the wire feeder). When the wirefeeder 120 is powered up, it can receive user inputs via the userinterface controls 126. These user inputs are communicated to thecommunication module 123 and the transmitter 125 which causes thecurrent sink circuit to vary the current draw by the wire feeder 120from the power signal from the power supply 110. That is, rather thansending a communication signal using a known communication protocol, thecurrent sink circuit 127 varies the current draw of the wire feeder 120so that the power supply 110 “sees” or senses the changes in the currentdraw—via the current sense lead 104 and receiver 105, and interpretsthese changes in the current draw as a data communication signal.

An exemplary current draw communication signal is represented in FIG. 2.FIG. 2 shows a current signal 200 having a low OCV current draw (below0.5 amps) when no communications are being made and the power supply 110is simply powering the wire feeder 120. However, when the wire feeder120 wants to communicate with the power supply 110—to communicate userinput settings for example—the wire feeder uses the current sink circuit127 to vary the current draw from the power signal in a series of pulsesas shown in the waveform 200. As shown in this exemplary embodiment, thecurrent sink circuit 127 causes the current draw from the power supplyto pulse to a peak level of about 2.5 amps in a series of pulses whichare recognized by the power supply 110 (sensing the changes in currentdraw) as a data signal from the wire feeder 120. The wire feeder 120uses these current draw pulses as a means to communicate data. Thus,unlike known communication systems, the wire feeder 120 does notgenerate a communication signal that is transmitted to the power supply(using various known communication protocols) but instead varies thecurrent draw in a predetermined format/pattern which is seen by thepower supply as a data signal. This is a more robust and stablecommunication protocol.

For example, in the exemplary embodiment shown, the communication module123/current sink circuit 127 causes a message start current pulse 201 tobe initiated. For this pulse (and subsequent pulses) the current sinkcircuit 127 switches to create a current path which causes the desiredadditional current to be drawn from the power signal to create the pulse201. This signal start current draw pulse 201 has a predetermined pulsewidth and/or peak current which is known by the power supply 110 as asignal start pulse. For example, as shown, the signal start pulse 201has a pulse width of 3 ms and a peak current of about 2.5 amps. Thus,when this current draw is sensed by the power supply 110, the powersupply 110 control module 101 recognizes that data is to be transmittedfrom the wire feeder to the power supply. Following the signal startpulse 201 a series of current draw pulses 203/205 are created by thecurrent sink circuit 127 and are sensed by the power supply 110. Thepulses 203/205 can represent a binary code (“1”s and “0”s) which arerecognized by the control module 101 of the power supply 110, such thatthe control module 101 interprets/uses these current draw pulses toreceive the data message from the wire feeder 120. For example, thepower supply 110 can use this message to provide the desired weldingsignal for a given welding operation. As shown, the data pulses 203/205can have a different pulse width and/or peak current so as to providethe desired binary code. In the embodiment shown, the pulses have thesame peak current, but their pulse width is varied, where one data pulse203 has a large pulse width than the other data pulse 205. Using thisbinary pulse methodology a binary signal can be sent to the power supply110 from the wire feeder 120 using nothing more than varying currentdraw at the wire feeder. In some exemplary embodiments, a signal endcurrent draw pulse (not shown) can be created by the circuit 127 tosignal the end of a data transmission to the power supply. For example,the signal end pulse can be the same as the signal start pulse 201, butbecause it is received second it is recognized as a signal end pulse. Inother embodiments, the signal end pulse can have a different peakcurrent and/or pulse width which is recognized at the power supply as asignal end pulse. In a further exemplary embodiment, the receiver 105and/or the control module 101 can have a predetermined bit size for apacket of information from the wire feeder, and when the appropriateamount of information (e.g., bits) is received from the wire feeder 120the control module 101 determines that a full packet has been sent andthen processes that packet and awaits for a further signal start pulse201. In such an embodiment, a signal end pulse is not needed. Further,in additional embodiments the signal start and/or end may not be asingle pulse, but can be two or more pulses of the same type—which isused to signal the beginning and/or end of a data packet. For example,embodiments can use two identical data pulses having certain pulsecharacteristics to signify the beginning of a data message.

The current draw pulses 201/203/205 utilized by embodiments of thepresent invention can have any predetermined pulse width/peak current solong as each of the power supply 110 and wire feeder 120 each recognizethe pulse data. For example, the pulses can have a peak current in therange of 0.25 to 5 amps, and can have a pulse width in the range of 0.05to 100 ms so long as the various pulses 201/203/205 are sufficientlydistinguishable from each other so as to be properly recognized by thepower supply 110. In further exemplary embodiments, the pulse widths canbe in the range of 0.5 to 5 ms, 1 to 3 ms. For example, in an exemplaryembodiment the signal start pulse 201 can have a pulse width of 3 ms,whereas the data pulses 203 and 205 can have pulse widths of 2 ms and 1ms, respectively. These pulses can have the same peak current, or canhave different peak currents in different exemplary embodiments. Inexemplary embodiments, the peak currents of the respective pulse can bein the range of 1 to 5 amps. In further exemplary embodiments, the peakcurrents for the pulses can be in the range of 2 to 4 amps. In exemplaryembodiments, the current draw signal can have a frequency in the rangeof 10 Hz to 10 kHz, while in other embodiments the range can be 100 Hzto 500 Hz. Of course, embodiments are not limited to these parametersand other pulse widths, peak currents and frequencies can be used solong as the communication protocol is recognizable by the power supply110. In other exemplary embodiments, the duration of the peak current ofthe pulses can be altered to distinguish between the different pulses,for communication purposes. That is, in such embodiments, the pulsewidth of each of the pulses is the same, but the duration of the peakvalue of the different pulses is different, and this differential isused by the power supply 110 to recognize the different pulses. Anynumber of different pulse types can be used to communicate data, wherethe pulses have different peaks and/or widths to distinguish the pulsesso long as they are recognizable by the power supply. Further, the pulseperiod or frequency can be used to differentiate pulse for datatransmission.

However, it should be noted that because the current sink circuit 127 isdrawing current from the OCV signal, the drawn power needs to bedissipated within the wire feeder 120. This can be done with the use ofresistors, or similar heat/energy dissipation components/techniques.Thus, the drawn power/current by the wire feeder 120 should in an amountthat can be dissipated by the wire feeder 120. That is, the amount ofpower to be dissipated in any given message (total current & voltageover the duration of the message) should be at an amount that can bedissipated without overheating any components. In exemplary embodimentsof the present invention, the average power of the data signal does notexceed 25 watts. In further exemplary embodiments, the average power ofthe current draw data signal is in the range of 5 to 25 watts. In afurther exemplary embodiments, the average power is in the range of 7 to20 watts. Of course, so long as a wire feeder 120 is capable ofdissipating more heat energy/power the average power of the current drawsignal can be higher than that discussed above.

To aid in dissipating the power (via generated heat) in thecommunication module 121, the wire feeder 120 can utilize an existingcooling fan (not shown) to cool any resister components used todissipate the energy. In other exemplary embodiments, a dedicatedcooling mechanism, such as a secondary fan, heat sink, etc. (not shown)can be used to cool the current sink circuit 127 during communication toproperly dissipate any generated heat due to power dissipation. Infurther exemplary embodiments, a temperature monitoring circuit (notshown) can be used to monitor the temperature of the circuit 127, orsome of its components. Such temperature monitoring circuits/systems aregenerally know. By monitoring the temperature the system controller canimplement certain protocols to control the heat of the circuit 127. Forexample, in some exemplary embodiments the controller can use thedetected heat—as compared to a predetermined heat threshold level—tocause an auxiliary cooling fan to be turned on to aid in cooling thedesired components. In further exemplary embodiments, the controller canuse the detected heat to stop the communication process, or alter thecommunication process to ensure a heat threshold level is not exceeded.For example, in some embodiments, an information packet can be sent tothe power supply to indicate that communication will stop for a time,and then the wire feeder controller can monitor temperature until suchtime as the temperature is acceptable and begin communicating again. Inother exemplary embodiments, the controller can change the current drawpulses to reduce the needed energy absorption. For example, thecontroller can cause the circuit 127 to reduce the peak current levelsof the pulses so that less energy is absorbed until the temperaturereaches an acceptable level and then the original pulse peaks can beused. Of course, the power supply 110 should be configured to recognizethese secondary pulse configurations as well. The change of the pulseparameters can be communicated from the wire feeder 120 to the powersupply 110 prior to the change so that the power supply 110 isappropriately configured to recognize the changed pulses. In a furtherexemplary embodiment, the controller of the wire feeder 120 has at leasttwo predetermined temperature thresholds levels. When a first heat levelis detected the controller determines that the communication must bestopped, additional cooling is needed, and/or the communications must bechanged so that the heat level is reduced. The second level is lowerthan the first level and when the second level is detected thecontroller then determines that normal communications can be resumed.This can allow the heat to sufficiently reduce before normal operationsare started again. It can be beneficial to have this second levelsufficiently low such that once normal communications are resumed thefirst level is not reached quickly.

As stated above, the power supply 110 uses the current sense circuit 104and receiver 105 to recognize the current draw pulses 201, 203 and 205and use those pulses to control the operation of the power supply 110consistent with the instructions from the wire feeder 120. The powersupply 110 uses this information to adjust its waveform, output settingsetc. to execute the desired welding operation.

Turning now to the communication from the power supply 110 to the wirefeeder 120, as similar communication protocol is used, except thatvoltage pulses are used, as opposed to current pulses. That is, inexemplary embodiments of the present invention, the power supply 110uses voltage pulses, within the supplied OCV voltage, to sendacknowledgments and/or other data to the wire feeder 120. For example,in some embodiments, the control module 101 can be configured to send anacknowledgment signal to the wire feeder 120 to indicate that the datapacket sent by the wire feeder 120 has been received. In such anembodiment, the wire feeder 120 can send a data packet (via the currentdraw pulses), and when is received by the power supply 110, the powersupply sends an acknowledgment pulse and/or message, and when thatacknowledgment is received by the wire feeder 110 it can send anotherdata packet. In some embodiments, if no acknowledgment is received bythe wire feeder 110, it resends the data packet. Of course, other datacan be sent to the wire feeder 120 via the following methodology aswell. In exemplary embodiments, the power supply 110 uses thetransmitter 107 to provide a voltage pulse signal to the output powermodule 103. The output power module 103 uses the voltage pulse signal tocontrol its output and provide voltage pulses, consistent with apredetermined communication protocol, to the wire feeder 120 via thepower cables 130. The control of the output power module is well knownand need not be described in detail herein.

An exemplary embodiment of a voltage communication waveform 300 is shownin FIG. 3. As shown in this Figure, a similar communication methodologyis employed as described with respect to FIG. 2, except rather thanusing current draw pulses, voltage pulses are employed. That is, as thepower supply 110 is providing an OCV voltage to the wire feeder (e.g.,prior to or after welding), the power supply 110 also provides voltagepulses 301, 303, and 305 to communicate information to the wire feeder.The pulses are sensed by the voltage sense lead 128 which couples thewire feeder 110 stud 113 to the receiver 129. These voltage pulses aresensed and converted to an informational signal to be used by thecontroller 121 of the wire feeder.

Turning now to FIG. 3, similar to the protocol discussed above, thepower supply 110 can output a message start voltage pulse 301 whichindicates to the wire feeder 110 that a message follows. The first pulse301 can have a particular set of parameters, such has pulse width,voltage level, voltage level duration and/or frequency which isrecognized by the wire feeder 120 as the beginning of a data message.Similar to FIG. 2, following the message start voltage pulse 301 are aseries of data voltage pulses 303 305 which are different from eachother so as to communicate a binary message to the wire feeder 110.

As shown in the example of FIG. 3, the OCV signal from the power supply110 has an OCV voltage of 60 volts. The voltage pulses 301, 303, 305each drop to about 20 volts, for a predetermined duration, and thisvoltage drop is detected by the receiver 129 and the controller 121 usesthe received pulses to control an operation of the wire feeder 110consistent with the received message/confirmation. As shown, 303 is afirst data pulse type having a first pulse width, and pulse 305 is asecond data pulse type having a second pulse width. In the embodimentshown, the voltage level of each of the pulse types are the same (in theembodiment shown, the pulse voltage is about 20 volts). Of course, inother exemplary embodiments the different pulse types can have differentvoltage levels and/or frequencies. For example, rather than changing thepulse widths of the pulses (as shown in FIG. 3), the pulses can have thesame pulse width but different voltage levels—e.g., pulses 303 have alevel of 20 volts and pulses 305 have a level of 40 volts. Of course, inother embodiments, other pulse parameters can be changed, so long as thepulses 303/305 are distinguishable from each other and can be recognizedas distinct pulses by the wire feeder 120.

As shown in FIG. 3, the voltage pulses from the power supply 110 to thewire feeder 120 are made in the OCV voltage signal from the power supply110 and have a voltage of about 20 volts, whereas the pulse widths ofthe different pulses are different. Of course, this embodiment isintended to be exemplary and in other exemplary embodiments, the voltagelevel of the pulses can be in the range of 1 to 70 volts so long as thepulses are recognizable as data pulses, while in other embodiments, thevoltage can be in the range of 10 to 55 volts. Of course, the voltagelevel of the pulses 301, 303 and 305 can be a function of the OCVvoltage level for the power signal provided to the wire feeder 120 fromthe power supply 110 when no welding operation is ongoing. In someexemplary embodiments, the voltage level for pulses is in the range of20 to 95% of the OCV voltage level of the non-welding power signal. Inother exemplary embodiments, the voltage level is in the range of 30 to90% of the OCV voltage level, and in further embodiments the voltagelevel is in the range of 33 to 75% of the OCV voltage level. Of course,it should be noted that the voltage level of the pulses can be at anylevel appropriate for a given system so long as the voltage level of thepulse is sufficiently recognizable by the receiver in the wire feeder soas to ensure that the sent data is accurately and reliably received. Inexemplary embodiments, the OCV voltage pulse signal can have a frequencyin the range of 100 Hz to 10 KHz. In further exemplary embodiments, thefrequency of the signal can be in the range of 1 to 5 KHz. In otherexemplary embodiments, the frequency is in the range of 100 Hz to 1 KHz.Further, similar to the current draw signal method, any number ofdifferent voltage pulse types can be used to communicate data, where thevoltage pulses have different peaks and/or widths to distinguish thepulses so long as they are recognizable by the wire feeder. Further, thepulse period or frequency can be used to differentiate pulse for datatransmission.

It is noted that in some exemplary embodiments, the voltage for thesignal pulses can drop to as low as 0 volts. However, in suchembodiments the signal duration should not be too long so as tocompromise the power being supplied to the wire feeder 110 to affect itsoperation.

The above methodologies described exemplary embodiments of communicationbetween a wire feeder and power supply of a welding system in which thestandard OCV power signal from the power supply to the wire feeder isused as a means to communicate between the components without the needfor complex communication protocols. That is, in exemplary embodiments,the wire feeder uses a varied current draw on the OCV signal, whereasthe power supply inserts voltage pulses within the OCV signal tofacilitate communication. As explained herein, embodiments of thepresent invention can use at least two different current draw/voltagepulses to communicate data between the welding system components, wherethe different pulses have at least one characteristic that is different.That is, the pulses can differ in at least one of pulse width,frequency, peak duration, and/or peak magnitude, so long as thedifference is sufficient to allow the respective receivers todistinguish between the pulses for accurate data transmission. Ofcourse, in other embodiments, any combination of these pulsecharacteristics can also be used to distinguish the data pulses. Forexample, a first data pulse can have a first pulse width and peak, andthe second type of data pulse can have a different pulse width and peak.Of course, other combinations can be used to differentiate the datapulses without departing from the spirit and scope of the exemplaryembodiments described herein. This communication methodology is highlyrobust and reliable.

Further, because of the mode of communication there is no practicallimit in the duration of messaging from the power supply 110 to the wirefeeder 120, so long as the on time of the OCV signal is sufficient.However, there may be limitations in the overall duration of themessages from the wire feeder 120 to the power supply 110. Because thewire feeder 120 is drawing current from the OCV signal as the messagingprotocol, that energy needs to be dissipated—as explained above, thiscan be done via heat dissipation. Thus, the messages from the wirefeeder 120 should be of a length to ensure appropriate heat/energydissipation by the wire feeder 120.

It should be noted that even though the above embodiments have beendescribed as communicating when there is no welding signal being sent tothe wire feeder 120 over the cables 130. In other exemplary embodimentsof the present invention, the wire feeder 120 can communicate with thepower supply 110 during welding using a similar communication protocolto that described above—current draw pulse. Of course, the current drawpulse messages from the wire feeder 120 to the power supply 110 are tobe configured so as to not interfere with the welding operation and thewelding waveform, communication can occur during welding. The currentdraw from a wire feeder motor (used for feeding the wire consumable)should also be considered to facilitate robust communication, as thecurrent needed for the motor may change due to changes in torquerequirements for the wire feeding. Therefore, in exemplary embodimentsof the invention, where the wire feeder 120 communicates with the powersupply during welding, the frequency of the current draw pulse messageshould be relatively low—so as to not interfere. For example, inexemplary embodiments, the frequency for the data signal should be inthe range of 20 to 100 Hz. That is, to the extent that the messagecontains multiple frequencies (as explained above) each of thefrequencies should be in the stated range. In other exemplaryembodiments, the frequency should be in the range of 30 to 70 Hz. Theserelatively low frequencies can be used to ensure no interference withthe welding operation during communication. Of course, in otherembodiments, other frequencies can be used so long as no interferenceoccurs, and can be dictated by the frequencies being used in the weldingoperation. Embodiments of the present invention can be used during alltypes of welding, including CC, CV, pulse, short arc, STT, etc., so longas the communication signal can be sufficiently distinguished from thewelding signal and will not interfere with the welding signal.

It should be noted that in further exemplary embodiments, more than onewire feeder (load) can be connected to the power supply. In suchembodiments, the data signal from the wire feeder includes wire feederidentification that is recognized by the power supply and is used to aidensuring that the power supply is providing the proper output to theproper wire feeder. Thus, in some embodiments a power supply can becoupled to, and able to communicate with, more than one wire feederusing the methods discussed herein.

FIGS. 4 and 5 provide additional detail regarding exemplary embodimentsof the current sink circuit 127. The depicted exemplary embodimentscontain switches 403 and 405, resistors 407, 409 and 411, and a currentshunt regulator 401 to regulate and absorb the current draw pulsesduring the messaging as described above. The current shunt regulator 401can be any known such regulator so long as it is capable of performingas desired. An example of such a regulator is the TL431 three-terminaladjustable shunt regulator from Texas Instruments. Of course, othersimilarly functioning components can be used. For example, in someexemplary embodiments an op-amp, MOSFET combination can be used insteadof the shunt regulator 401. Further, in additional embodiments the loadresistor 409 can be switched in or out (using known switching circuitry)based on an input voltage to improve performance as needed. In thecircuits shown in FIGS. 4 and 5, the resistor 409 provides a bulk of theenergy dissipation during the generation of the current draw pulses inthe wire feeder.

In the FIG. 5 embodiment, a full bridge rectifier 500 is added to thecircuit so as to add connection flexibility to the output studs of thepower supply 110. That is, with the use of the rectifier 500, theflexibility of the connections to the positive and negative terminals ofthe power supply 110 is increased. Of course, it is understood thatother exemplary circuits can be used to accomplish the same functions asdescribed above, and these circuits can be used without departing fromthe spirit or scope of the inventions described herein.

Because of the attributes and configurations discussed above, exemplarysystems of the present invention can provide significant advantages overknown welding systems. That is, using embodiments of the presentinvention, the wire feeder and power supply can communicate with eachother without separate communication cables and do so with increasedrobustness and utility of the welding system. Further, thiscommunication and data transmission occurs without adversely affectingthe welding signal or welding operation, even though the data is beingtransmitted over the same welding cables as the welding signal.

As stated above, each of the wire feeder 120 and the power supply 110use a controller which can employ a computer or microprocessor typesystem which executes various programs to facilitate the communicationsprotocols described herein. A computer program (e.g., a computer programsystem) can be written in any form of programming language, includingcompiled or interpreted languages, and it can be deployed in any form,including as a stand-alone program or as a module, component,subroutine, or other unit suitable for use in a computing environment. Acomputer program can be deployed to be executed on one computer or onmultiple computers at one site or distributed across multiple sites andinterconnected by a communication network.

Turning now to further exemplary embodiments which provide a system andmethod of comprising receiving continuously worksite voltage measurementdata of voltage at a welding electrode, where the worksite voltagemeasurement data is communicated across the arc using a welding cableand comparing continuously the worksite voltage measurement data to awelding output voltage at the welding power supply to identify a voltagedifference. The communication methodology can be those described above.The method also includes increasing or decreasing the welding outputvoltage using the welding power supply based at least in part on thevoltage difference.

Further embodiments provide a welding system comprising a wire feederhaving a workpiece lead connection and a weld cable connection, the weldcable connection configured to operatively couple the wire feeder to apower supply, the workpiece lead connection configured to complete acircuit between the wire feeder and a workpiece. The system furtherincludes a worksite voltage measuring component operatively coupled withthe wire feeder, the worksite voltage measuring component continuouslydetermines a worksite voltage measurement. In such embodiments the wirefeeder is configured to receive the worksite voltage measurement, andthe wire feeder is configured to transmit the worksite voltagemeasurement data through at least one of the weld cable connection andthe workpiece lead connection.

As explained above, various types of communication can occur between thesystem components, including relaying information related to a weldingoperation, such as voltage and current detections across the arc, andother aspects of a welding operation, including cable impedance changes,etc.

As stated above, embodiments of the present invention can be used to in“across the arc” welding arrangements. Like embodiments described above,across the arc arrangements are such that one pair of cables run fromthe power supply to the workpiece to provide both power andcommunication, with one connected to the workpiece and the otherunattached awaiting the wire feeder. The wire feeder is plugged in, withits own lead that clamps to the workpiece, and communicates over thework lead with the distant power supply without the use of additionalcontrol cables. Across the arc arrangements reduce the complexity,weight, accessory expense, and possible points of failure for weldingsystems.

Various practical characteristics of a welding system can impact theperformance of a welding system and these characteristics and data andcan sent via the communication protocols described herein. When seekingto weld in a particular manner or improve weld quality, weld settingsassociated with particular welding waveforms can be selected andcommunicated. In accordance with such waveforms and other weldingparameters, a welding power supply powers the welding operation.However, the parameters are based on expected or ideal conditions.

In some situations. a deviation from expected or ideal conditions in“Across the Arc” and other welding system arrangements is that cableimpedance can cause a voltage drop between the power supply and the wirefeeder, such that the power supply output voltage is set to therequirement of the wire feeder but the wire feeder power input is notactually receiving the prescribed voltage. The voltage drop due to theimpedance varies depending on the length and composition of thecable(s), geometry of the cables (coiled versus extended), weldingcurrent supplied, welding waveform and weld parameters, and otherfactors. Thus, a simple voltage offset at the power supply will notconsistently compensate for discrepancies from an expected output at thewelding tool, because such discrepancies can be dynamic in nature.

To monitor this variable discrepancy, an electrical measuring device(including, but not limited to, a voltmeter, multimeter, or other deviceor component) can be placed at or integrated into the wire feeder todetermine the voltage at the wire feeder. This voltage can betransmitted back to the power supply (or another device in communicationwith the power supply) across the arc and compared to theexpected/welding voltage or via the communication protocols describedherein. Such comparison can be conducted continuously and in real-time.The power supply operation parameters can then be adjusted to ensure theprecise appropriate voltage (or other parameter) is provided to the wirefeeder. In some embodiments, this is a repeated feedback processes whichdetermines average voltage drop over a period of time until the averagedrop is based on sufficient data to substantially equal (in magnitude)the average voltage drop as opposed to continuously adjusting accordingto an instantaneous or most-recently-detected voltage drop.

Communication in embodiments disclosed herein can occur via themethodologies described herein. This provides simple communication asadditional control wires can be cumbersome in many environments, andwireless communication is not always feasible (e.g., in shipyards whereline-of-sight is a problem or multiple power supplies may be presentrequiring pairing between different wireless devices before use). Thisarrangement minimizes the number of wired connections while providingplug-and-play capability for wire feeders.

FIG. 6 is an example circuit representation 1100 of a welding outputcircuit path, such as that illustrated at 1205 of FIG. 7 and otherdrawings, in accordance with an embodiment of the present innovation.The circuit representation 1100 includes an inductance Lc 1110 and aresistance Rc 1120 of the welding cable 1220 side of the welding outputcircuit path 1205. These values can (but need not exclusively) bedefined by the characteristics of welding cable 1220. The circuitrepresentation 1100 also includes an inductance Lm 1130, an internalresistance Ri 1140, and a diode D1 1150 of the welding power supply 1210side of the welding output circuit path 1205. These values can (but neednot exclusively) be defined by the characteristics of the welding powersupply 1210, alone or in conjunction with wire feeder 1270 (e.g., themachine side). The welding cable 1220 connects to the welding powersupply 1210 at the welding output 1212 having electrical nodes 1160 and1170, and a workpiece can be located in the vicinity of welding outputterminals 1191 and 1192.

When a current (I) 1180 flows through the welding output circuit path1205, an output voltage (V) 1165 is produced between the nodes 1160 and1170. Impedance from a power supply can be predetermined (e.g., due tothe machine output choke and dependent on current), but externalimpedances from outside the power supply (or other externalities) cannotbe known or forecast at the power supply in all circumstances. Becauseat least characteristics of welding cable 1220 are not static—theorientation and/or serviceability of welding cable 1220 change withtime, and furthermore, different cables (having different, e.g.,lengths, diameters, wear and tear, and other qualities) can be used withthe same welding power supply 1210. Thus, the total impedance of thesystem changes with time based on cables.

The varying impedance can cause voltage discrepancies at various pointsin the system, to include differences between the expected and actualvoltage at the welding electrode or workpiece. Various techniques ofdetermining voltage discrepancies are described herein. In some (but notnecessarily all) embodiments, power supplies, wire feeders, tools, orindependent electrical feedback devices can determine a discrepancybetween an actual electrical characteristic and the expectedcharacteristic based on power supply settings and the overall weldingsystem. In one or more specific embodiments, wire feeders includevoltage feedback capabilities for determining a voltage error ordiscrepancy caused by welding cable impedance, determining thedifference between the expected voltage at the measurement site (e.g.,at the workpiece, from the power supply, other values) and the actualvoltage at the measurement site (e.g., actual voltage at workpiece,actual voltage in welding tool, actual voltage detected by wire feeder,and others).

Electrical measurements (e.g., a voltage measurement at a wire feeder orwelding tool) can be transmitted across the arc, thereby eliminating theneed for separate control wires or complex wireless communicationtechniques. Connecting welding cables into the system will enablecommunication using such welding cables and enable feedback related toat least the electrical measurements. This is beneficial in many weldingarrangements, including those (such as Surface Tension Transfer) whichcan optionally use separate sensor and/or control leads in addition towelding cables. Across the arc techniques allow for an improvement inperformance while reducing the total system complexity as well aseliminating sources of error and points of failure.

Turning to such an embodiment, FIG. 7 illustrates a schematic blockdiagram of an example embodiment of a welding system 1200 including awelding output circuit path 1205, in accordance with various aspects ofthe present innovation. The welding system 1200 includes a welding powersupply 1210 having a welding output 1212, a comparator component 1216,and, optionally, a display 1214. The welding output circuit path 1205 isconnected to the welding power supply 1210 at the welding output 1212.

In accordance with an embodiment, the welding output circuit path 1205includes a welding cable 1220, a welding tool 1230, a workpiececonnector 1250, a spool of welding wire 1260, a welding wire feeder1270, a welding wire 1280, welding electrical measurement component1290, and an optional workpiece 1240. Welding cable 1220 includes leadsfor connections to welding tools and/or an optional workpiece 1240.

During operation, the welding wire 1280 is fed into the welding tool1230 from the spool of welding wire 1260 via the wire feeder 1270, inaccordance with an embodiment. In accordance with another embodiment,the welding system 1200 does not include a spool of wire 1260, a wirefeeder 1270, or a welding wire 1280 but, instead, includes a weldingtool comprising a consumable electrode such as is used in, for example,stick welding. In accordance with various embodiments of the presentinnovation, the welding tool 1230 may include at least one of a weldingtorch, a welding gun, an electrode holder, and a welding consumable.

The welding output circuit path 1205 runs from the welding output 1212of the welding power supply 1210 through the welding cable 1220 to thewelding tool 1230, through the workpiece 1240 and/or to the workpiececonnector 1250, and back through the welding cable 1220 to the weldingpower supply 1210. During operation, the welding power supply 1210 mayapply a welding output waveform to the welding output circuit path 1205,causing a time-varying electrical current to run through the weldingoutput circuit path 1205 and creating an arc between the wire (orelectrode) and the workpiece 1240. In accordance with an embodiment ofthe present innovation, the welding cable 1220 comprises a coaxial cableassembly. In accordance with another embodiment of the presentinnovation, the welding cable 1220 comprises a first cable lengthrunning from the welding power supply 1210 to the welding tool 1230, anda second cable length running from the workpiece connector 1250 to thewelding power supply 1210.

One portion of data capable of being transmitted over the welding cable1220 are electrical measurements from electrical measurement component1290. Electrical measurement component 1290 can measure an electricalvariable value at the worksite at or on an optional workpiece 1240, ator near wire feeder 1270, or elsewhere. In an embodiment, electricalmeasurement component 1290 takes one or more voltage measurements (e.g.,at the workpiece, at another location) and transmits the voltage valuesback to welding power supply 1210 by transmitting through welding cable1220. While electrical measurement component 1290 is shown as being inthe vicinity of welding tool 1230, electrical measurement component 1290can be standalone or integrated into various other components (e.g.,within wire feeder 1270).

Comparator component 1216 (or other components of welding power supply1210) can compare values measured by electrical measurement component1290 to those expected based on output at welding output 1212. Based onthis comparison, comparator component 1216 can calculate an electricalsignal discrepancy between the expected and actual electricalmeasurements. In an embodiment, the discrepancy is a voltage difference.Based on the voltage difference, welding power supply 1210 can increaseor decrease welding output voltage to compensate for the voltagedifference due to, e.g., cable inductance and other systemcharacteristics.

FIG. 8 depicts an alternative embodiment of a welding system 1500 usingtechniques described herein. Welding system 1500 includes welding wirefeeder 1570, welding cable 1520, welding tool lead 1521, and workpiecelead 1522. Welding system 1500 can also optionally include welding powersupply 1530, welding tool 1510, and/or welding workpiece 1540. Powersource 1530 includes a comparator component 1516 and is communicativelycoupled with electrical measurement component 1590 at least via weldingcable 1520. In this regard, communication can occur across the arc.

Electrical measurement component 1590 records an actual electricalmeasurement within the welding circuit and transmits the electricalmeasurement back to comparator component 1516 which analyzes the actualelectrical measurement in view of an expected electrical value. Based onthe difference in the actual and expected values, welding parameters canbe modified. This can include transmitting a signal to power supply 1530to increase or decrease a welding voltage provided through welding wirefeeder 1570 based on a voltage discrepancy.

While welding system 1500 depicts welding wire feeder 1570 as thecentral component of the system with other elements optional, variouscombinations of elements depicted can be utilized without departing fromthe scope or spirit of the innovation. For example, welding wire feeder1570 and welding power supply 1530 can be a combined unit. Further,while comparator component 1516 is shown as integrated within weldingwire feeder, this component can be present in other elements inalternative embodiments, including power supply 1530, welding tool 1510,or electrical measurement component 1590. In at least one embodiment, anexpected voltage value is transmitted using welding cable 1520 to permitcomparator component 1516 to complete comparison of a measured value ata location outside welding wire feeder 1570 (and/or welding power supply1530). Furthermore, each of the wire feeder and/or the power source canhave a user interface to allow a user to interact with the system andcomponents and input data and parameters and read information andparameters.

FIG. 9 illustrates a further embodiment similar to that of FIG. 8wherein welding system 1600 includes an electrical characteristic signalprocessor 1692. In embodiments, electrical characteristic signalprocessor 1692 can be a voltage signal processor. Electricalcharacteristic signal processor 1692 can transform a measured electricalcharacteristic (e.g., from electrical measurement component 1590) intoanother format. In embodiments, electrical characteristic signalprocessor 1692 transforms a measured electrical characteristic into acompressed size signal to reduce the bandwidth required by itstransmission. In an embodiment, electrical characteristic signalprocessor 1692 creates a compressed size voltage data to transmit avoltage value for comparison. In alternative or complementaryembodiments, electrical characteristic signal processor 1692 can changethe format of a measured electrical characteristic to include encoding,encrypting, or re-formatting.

Modification of a measured electrical characteristic can enable expandeduse of across the arc communication. In an example, surface tensiontransfer and other short-arc welding processes can include sense leadsto provide information back to the power supply to perform the rapidcalculations for control of these operations. Reliance on welding cable1520 in lieu of sense leads may at times result in insufficientbandwidth to provide the realtime feedback required for control ofcomplex processes. Incorporation of additional circuitry for measuringparameters and performing calculations at, e.g., wire feeder 1570(and/or other components) can permit larger data portions to bereceived, processed, and analyzed therein, with smaller control signalsconforming to the bandwidth available using welding cable 1520 sent backto power supply 1530 (and/or other components) which adjusts accordingto these smaller signals. This allows for more decisions or controlsteps to be performed at a lower bandwidth per decision or control step,increasing the speed of control. This can include converting an analogparameter signal such as voltage to a digital signal before provisioningto the power supply using the power cable.

In a specific embodiment, voltage over time can be measured realtime atwire feeder 1570. The wire feeder can include comparator component 1516,and either include or be operatively coupled with electrical measurementcomponent 1590 and electrical characteristic signal processor 1692. Oneor more of these components can perform a calculation to produce atrigger including a compressed size signal comprising a smaller portionof information than would be required if all parameters were measured atwire feeder 1570 or (optional) workpiece 1540. The trigger is sent topower supply 1530 for use in calculations or adjustments. Inembodiments, the trigger may be sent to alternative or additionalcomponents (e.g., welding wire feeder 1570, comparator component 1516,others) for use in calculations or adjustments. In another suchembodiment, the instantaneous voltage or voltage difference is providedin realtime to welding wire feeder 1570 and/or power supply 1530 throughthe welding cable 1520. In embodiments, such as those described above,having the comparator in the wire feeder can allow the wire feeder to doa welding signal comparison and then send a set point (via thecommunications described herein) back to the wire feeder. For example,the comparator can be used to compare the detected welding voltage to adesired voltage set point (that was previously communicated to or set atthe wire feeder) and then rather than sending the detected voltage tothe power supply, the wire feeder does the comparison and sends a newvoltage set point for the power supply. The power supply then changesits output power based on the new set point. Of course, other weldingparameters such as current can also be changed in this way.

In an embodiment, control can be bifurcated into an “inner loop” and“outer loop,” with inner loop control occurring at wire feeder 1570 andouter loop controls occurring at power supply 1530. For control thatmust be performed in real time, such as controlling the timing ofsurface tension transfer processes, the, high speed control is done bythe wire feeder 1570. Less time-critical processes controls would bedone by power supply 1530. The power supply control utilizes parametersand other data are sent back to power supply 1530 which uses onboardcontrol circuitry for processing and responding to such therein.Information between wire feeder 1570 and power supply 1530 can be sentvia welding cable 1520 in such embodiments.

In an embodiment, at least a portion of a control circuit for a powersupply is moved to the wire feeder, and communicates with the powersupply over the power cable. In an alternative or complementaryembodiment, another high speed communication link can be included. Forexample, wire feeder and power supply could pair using the cable andthereafter communicate at least in part wirelessly. Alternative highspeed communication links are also possible to use.

In accordance with other alternative embodiments, the various functionalaspects of determining the electrical characteristics of a weldingoutput circuit path and selecting a welding output waveform based on theelectrical characteristics may be distributed between the welding powersupply and the welding output analyzer in various ways, dependent onprudent design judgment, cost restrictions, and/or other considerationsand tradeoffs.

FIG. 10 is a flowchart of an example embodiment of a method 1700 formodifying an output electrical characteristic at a welding power supply.Method 1700 begins at 1710 and proceeds to 1720 where worksite voltagemeasurement data at a welding electrode (or nearby component) isreceived (by, e.g., a wire feeder, power supply, or other componentincluding components for processing the information). Methodology 1700then proceeds to 1730 to compare the worksite voltage measurement datato a welding output voltage at the welding power supply to identify avoltage difference. Thereafter at 1740, an increase or decrease thewelding output voltage is applied using the welding power supply basedat least in part on the voltage difference.

In further exemplary embodiments of the present invention, the wirefeeder is capable of sending a trigger signal (for example, usingcommunication protocols discussed above) to the power supply in responseto detecting an event at the feeder. The trigger is a quick/short signalthat is recognized at the power feeder as indicating that such apredetermined event has occurred. For example, in certain weldingapplications, such as STT, it is desirable to detect when the derivativeor rate of change of the voltage (dv/dt) exceeds a predetermined valuein a short circuit. This predetermined value can be representative of acritical event in the welding waveform, requiring a response from thepower supply on the welding waveform. In known systems, to detect thistype of voltage change remote sense leads are needed. However, inexemplary embodiments of the present invention, the remote sense leadsare eliminated. That is, in exemplary embodiments, the wire feedercontains a detection circuit (such as a known voltage derivativedetection circuit) which detects the type of predetermined event to bemonitored for (for example the voltage derivative discussed above). Suchdetection circuits are known. When the event is detected via thedetection circuit, the detection of the event is communicated via the“trigger” signal over the welding cables. In exemplary embodiments, thewire feeder uses the above described current draw modulation technique.The trigger event is recognized at the power supply as indicating thatthe event has occurred, and in exemplary embodiments, the power supplydoes not send a response back but responds to or otherwise changes itsoutput signal/power based on the trigger event being communicated. Thus,unlike some of the other embodiments described herein, rather than afull digital signal being sent via current draw pulses, a singlepredetermined event is signaled via the trigger communication and thepower supply reacts to that trigger signal. In exemplary embodiments,the trigger signal is a single current pulse having predeterminedproperties, which would look like a step change in current to the powersupply. For example, in some exemplary embodiments the trigger currentdraw pulse can have a peak current in the range of 2 to 10 amps, and inother embodiments can have a peak current in the range of 3 to 7 amps.Further, the current pulse can have a pulse width in the range of 0.25to 3 ms, and in other embodiments, the pulse width is in the range of0.5 to 1.5 ms. In such embodiments, the power source recognizes thetrigger current pulse (instead of, for example, waiting to see thechange in derivative voltage) to change its output. In other exemplaryembodiments rather than a single pulse a plurality of pulses can beused, but again the overall signal is short so as to minimize reactiontime by the power supply.

In exemplary embodiments, the trigger pulse can indicate differentevents depending on the welding operation being performed. That is, whena particular type of welding operation is selected (for example STT),the power supply then recognizes the trigger event to be representativeof a particular type of dv/dt detection. However, in other weldingoperations, the trigger event can represent a different type of event,such as the measured voltage exceeding a peak value, etc. Thus, when thetrigger event is detected at the wire feeder, the trigger pulse is sentto the power supply which is recognized and reacts consistent with itpredetermined protocol. Of course, in such embodiments the wire feedercomprises the detection circuits, such as comparators, etc. which arecapable of detecting and comparing a voltage, voltage derivative,current and/or current derivative as needed for the desired detectionevent. Such detection and comparison circuits are known and need not bedescribed here in detail.

In summary, systems and methods for selecting a welding output based onmeasured electrical characteristics in a welding output circuit path aredisclosed. A discrepancy or difference between expected and measuredelectrical values can be discerned and communicated across the arc topermit adjustment of at least a welding power source to compensate forthe difference or discrepancy.

Method steps can be performed by one or more programmable processorsexecuting a computer program to perform functions of the invention byoperating on input data and generating output. Method steps can also beperformed by, and apparatus can be implemented as, special purpose logiccircuitry, e.g., an FPGA (field programmable gate array) or an ASIC(application specific integrated circuit). Modules can refer to portionsof the computer program and/or the processor/special circuitry thatimplements that functionality.

Processors suitable for the execution of a computer program, includingthe communication protocols discussed herein, include, by way ofexample, both general and special purpose microprocessors, and any oneor more processors of any kind of digital computer. Generally, aprocessor will receive instructions and data from a read-only memory ora random access memory or both. The essential elements of a computer area processor for executing instructions and one or more memory devicesfor storing instructions and data. Generally, a computer will alsoinclude, or be operatively coupled to receive data from or transfer datato, or both, one or more mass storage devices for storing data, (e.g.,magnetic, magneto-optical disks, or optical disks). Data transmissionand instructions can also occur over a communications network.Information carriers suitable for embodying computer programinstructions and data include all forms of non-volatile memory,including by way of example semiconductor memory devices, e.g., EPROM,EEPROM, and flash memory devices; magnetic disks, e.g., internal harddisks or removable disks; magneto-optical disks; and CD-ROM and DVD-ROMdisks. The processor and the memory can be supplemented by, orincorporated in special purpose logic circuitry.

To provide for interaction with a user on the wire feeder and/or thepower supply, the above described techniques can be implemented on a CNCor computer having a display device, e.g., a CRT (cathode ray tube) orLCD (liquid crystal display) monitor, for displaying information to theuser and a keyboard and a pointing device, e.g., a mouse or a trackball,by which the user can provide input to the computer (e.g., interact witha user interface element). Other kinds of devices can be used to providefor interaction with a user as well; for example, feedback provided tothe user can be any form of sensory feedback, e.g., visual feedback,auditory feedback, or tactile feedback; and input from the user can bereceived in any form, including acoustic, speech, or tactile input.

The above described techniques can be implemented in a distributedcomputing system that includes a back-end component, e.g., as a dataserver, and/or a middleware component, e.g., an application server,and/or a front-end component, e.g., a client computer having a graphicaluser interface and/or a Web browser through which a user can interactwith an example implementation, or any combination of such back-end,middleware, or front-end components. The components of the system can beinterconnected by any form or medium of digital data communication,e.g., a communication network. Examples of communication networksinclude a local area network (“LAN”) and a wide area network (“WAN”),e.g., the Internet, and include both wired and wireless networks.

Comprise, include, and/or plural forms of each are open ended andinclude the listed parts and can include additional parts that are notlisted. And/or is open ended and includes one or more of the listedparts and combinations of the listed parts.

As stated above, although the majority of the discussion in the presentapplication has been discussed within the context of welding powersupplies and wire feeders, these discussions were exemplary. In otherwords, while the invention has been particularly shown and describedwith reference to exemplary embodiments thereof, the invention is notlimited to these embodiments. It will be understood by those of ordinaryskill in the art that various changes in form and details may be madetherein without departing from the spirit and scope of the invention asdefined herein.

We claim:
 1. A welding system, comprising: a welding power sourcecomprising a controller having a first receiver and a first transmitter;a wire feeder comprising a communication circuit having a secondreceiver, a second transmitter, and a current sink circuit having acurrent shunt regulator and switches; and at least one welding powercable coupled to each of the welding power source and the wire feederand configured to carry a welding power from the welding power source tothe wire feeder during a welding operation; wherein the wire feeder isconfigured to communicate with the welding power source over the atleast one welding power cable by generating a current draw signal, viaat least the current sink circuit of the wire feeder, which is detectedby at least the first receiver of the welding power source via currentsensing; wherein the welding power source is configured to communicatewith the wire feeder over the at least one welding power cable bygenerating a voltage pulse signal, via at least the first transmitter ofthe welding power source, which is detected by at least the secondreceiver of the wire feeder via voltage sensing; wherein the currentdraw signal comprises a plurality of current draw pulses generated atthe wire feeder and the voltage pulse signal comprises a plurality ofvoltage pulses generated at the welding power source.